For the past week I have had £31 to spend on food. Supermarket basics-range cornflakes and coffee have been my breakfast, home-made ham sandwiches my lunch, and for dinner I have been living off a big chilli I made early in the week, and buying frozen pizzas.

Fresh fruit, snacks and afternoon coffee have been off the menu. For the first time in my life I found myself counting the slices of bread in a loaf, to make sure I’d have enough to last.

My “living allowance” for the week was £175. According to Giselle Cory, of the Resolution Foundation, this is the average income of someone at the bottom end of the UK’s low-to-middle income bracket, which comprises 11 million UK adults.

Contemplating my budget last Saturday morning, £175 sounded like a fair sum. But after allowing for rent; council tax; energy and water bills; TV, internet and mobile phone fees; and the costs of travelling to work (all the things a working man living in Britain in 2013 might reasonably expect to have to pay), I was left with just £31.

As I walked from the bus stop each day (no Tube journeys for me) to The Independent’s office in Kensington, I would pass some of the most expensive properties in the country and some very fine restaurants. Hands-in-pockets and unable even to contemplate a starter from the menus, it was galling to think that the people inside were spending more for one meal than I could spend on food all week.

Of course, it’s hardly surprising that in Britain today the sum of money one person treats like spare change is the same sum another person clings to so that they don’t go hungry – but it had never seemed quite so unfair before.

Three things made my week miserable. First, not being to get around town to meet friends and family is depressing: I agonised over whether to go out for my sister-in-law’s birthday, and when I decided to go I knew that a Tube journey and a pint would mean less food later on. Sure enough my early extravagance meant I had to skip lunch on Friday.

Second, eating a small amount of poor-quality food for a week leaves you tired, irritable and, yes, hungry.

Third, and worst of all, I was aware that one unexpected piece of expenditure – a bank charge, for instance – would tip me over the edge and I would not be able to afford food at all.

Today I am lucky enough to wake up and make full use of my salary again. But for millions of people in the UK the kinds of dilemma I faced this week, and the fear that a sudden change in circumstances could leave them without food on the table, are a constant.

If I were a parent, I would not have taken part in this experiment, not even for a week. Thousands of parents don’t have a choice.

One week ago a Conservative councillor from York said that no one is starving in the UK. On the evidence of last week, he is wrong. Not because the income used in our experiment was a starvation rate, but because for those who have to exist on such precarious incomes it does not take much to push them over the edge.

“Lots of people living on the breadline are getting by most of the time, but then some kind of crisis hits,” says Molly Hodson of the Trussell Trust, the charity whose network of 298 food banks has given out more than 209,000 emergency food packages since April.

“Say you’re off work for a week and you end up on statutory sick pay, or your car breaks down and you don’t get to work and lose your job. Then the crisis spirals into a disaster. Even something as simple as cold weather: a lot of people on low incomes are on meters for electricity and gas. Whenever there’s a bout of very cold weather, people are making the decision between heating and eating.”

Food banks are not somewhere people can go if they fancy saving a few pennies on the weekly shop – they are crisis centres. To be given the standard three-day food package, you have to be referred by a front-line professional: a social worker, nurse, doctor, debt counsellor or even a police officer. Hundreds of referrals are being made each day by the people on the front line of Britain’s growing poverty crisis.

At the end of my week I came face to face with people genuinely suffering on a visit to my local food bank, at the All Nation’s Church in Clapham.

Staffed by volunteers who tend to be on very low incomes themselves, it opens twice a week. On Christmas Eve, the bank fed 125 people, its manager Lydia Serwaa said.

As I got there yesterday, more than a dozen people were arriving, food vouchers in hand. One of the first was Pedro, 34 (not his real name, but understandably he’d prefer to remain anonymous). Housing benefit and jobseekers allowance bring in £157 a week for him. An £80 penalty fare incurred from Transport for London after he lost his travel card had tipped him over the edge. “It was a choice between paying the fare and eating,” he said.

Talk at the food bank centred on the coming cuts to welfare. From this year, payments will be limited to a 1 per cent annual increase – a real-terms cut given current inflation rates. The Institute for Fiscal Studies predicts that 2.5 million families will be £215 worse off by 2015-16. That’s £4.13 a week.

It sounds like a pittance, but for many that could equate to one day’s food budget. Things are already beginning to bite. In the two weeks before Christmas 2011, the Trussell Trust gave out 8,500 emergency packages. This Christmas, it was 27,000. With inflation stuck at 3 per cent, well above the rate of pay increases, and with benefit cuts set to take effect later in the year, the situation could get very much worse if nothing is done.

One woman who visited yesterday has two-month old twins. She was referred to the food bank by the children’s centre she attends. When she arrived for the first time, she wasn’t even wearing any shoes.

Suddenly, one lean week on basics cornflakes and frozen pizzas seemed like a pretty pathetic attempt to imagine what poverty is like. Conservative councillors can deny it all they like – but people are starving in the UK.

Disposable income: Life at the sharp end

Charlie’s weekly income, based on that of a typical single working man in the bottom end of the low to middle income group of UK earners.

Salary: £111.42 (18 hrs a week on £6.19 minimum wage)

Housing benefit: £58.87

Council tax benefit: £5.36

Not eligible for income support, working tax credits, non means-tested benefits or jobseekers allowance.

Total: £175.65

* Housing benefit, council tax benefit, rent and council tax adjusted to reflect high London rents.

Source: The Resolution Foundation

On a budget: Charlie’s week

Saturday

With only £175 to spend, once I’d budgeted for rent (£100.50), gas and electricity (£7.10), water (£1.98), TV licence (£5.60), internet (£2.24), phone (£6.50) and transport (£20), I’m left with £31.08. Buy milk, coffee, pasta, chopped tomatoes, an onion, a carrot and cooking bacon for £4.78. Blow £4.20 on the Tube for a “night out” (manage to cadge a pint).

Sunday

£22.10 left. I eat yesterday’s pasta leftovers for lunch and a £2.50 pizza for dinner. Should have got a frozen one. Bread and ham for sandwiches for the week cost £3.60.

Monday

£16 left. Supplies of Sainsbury’s Basics crumpets I have been eating for breakfast run out.

Spend £5.77 on my last major shopping trip, getting ingredients for a chilli that will last me three days, and also some Basics cornflakes.

Tuesday

£10.23 left. Spend nothing on food but £4.40 on the Tube to have a drink with friends. They buy me a pint.

Wednesday

£5.83 left. Spend no money that I hadn’t already budgeted for, but run out of chilli.

Thursday

Really getting quite hungry by this point and the thought of another ham sandwich makes me feel sick. £2.20 on frozen pizza for dinner. Run out of bread and ham.

Friday

Decide to skip lunch and buy a decent dinner for £3.63. Can’t wait for Saturday.